Add expansion of shorthands with custom properties to longhands using a pending substition value.

third_party/WebKit/Source/core/css/StylePropertySerializer.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Research In Motion Limited. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
 */
 
 #include "core/css/StylePropertySerializer.h"
 
 #include "core/CSSValueKeywords.h"
 #include "core/StylePropertyShorthand.h"
 #include "core/css/CSSCustomPropertyDeclaration.h"
+#include "core/css/CSSPendingSubstitutionValue.h"
 #include "core/css/CSSPropertyMetadata.h"
 #include "core/css/CSSValuePool.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/text/StringBuilder.h"
 #include <bitset>
 
 namespace blink {
 
 StylePropertySerializer::StylePropertySetForSerializer::StylePropertySetForSerializer(const StylePropertySet& properties)
     : m_propertySet(&properties)
@@ skipping 327 matching lines @@
 
         hasImportant |= value.isImportant();
         hasNonImportant |= !value.isImportant();
         longhands[i] = value.value();
     }
 
     if (hasImportant && hasNonImportant)
         return emptyString();
 
     // TODO(timloh): This should be isCSSWideKeyword()
-    if (longhands[0]->isInitialValue() || longhands[0]->isInheritedValue()) {
+    if (longhands[0]->isInitialValue() || longhands[0]->isInheritedValue()
+        || longhands[0]->isPendingSubstitutionValue()) {
         bool success = true;
         for (int i = 1; i < longhandCount; i++) {
             if (!longhands[i]->equals(*longhands[0])) {
                 // This should just return emptyString() but some shorthands currently
                 // allow 'initial' for their longhands.
                 success = false;
                 break;
             }
         }
-        if (success)
+        if (success) {
+            if (longhands[0]->isPendingSubstitutionValue())
+                return toCSSPendingSubstitutionValue(longhands[0])->shorthandValue()->cssText();
             return longhands[0]->cssText();
+        }
     }
 
     bool allowInitial = allowInitialInShorthand(shorthand.id());
     bool allowImplicitInitial = allowInitial || allowImplicitInitialInShorthand(shorthand.id());
     for (int i = 0; i < longhandCount; i++) {
         const CSSValue& value = *longhands[i];
         if (value.isImplicitInitialValue()) {
             if (allowImplicitInitial)
                 continue;
             return emptyString();
         }
         if (!allowInitial && value.isInitialValue())
             return emptyString();
         // TODO(timloh): This should also check unset
         if (value.isInheritedValue())

[Timothy Loh, 2016/06/22 00:06:11]

Probably need to also check for pending substitution values here. This is for a
case like:

-> e.style.cssText = 'margin: var(--x); margin-top: 10px'

-> console.log(e.style.cssText)
(firefox outputs the following, looks crazy but I think it's spec compliant)
margin-right: ; margin-bottom: ; margin-left: ; margin-top: 10px;

-> console.log($0.style.marginLeft)
-> console.log($0.style.margin)
(empty string for both as per spec)

Let's also have some sort of test for this stuff.

[Andy Mutton, 2016/06/24 04:53:26]

Done.

             return emptyString();
     }
 
     return String();
 }
 
 String StylePropertySerializer::getPropertyValue(CSSPropertyID propertyID) const
 {
     const StylePropertyShorthand& shorthand = shorthandForProperty(propertyID);
     // TODO(timloh): This is weird, why do we call this with non-shorthands at all?
@@ skipping 256 matching lines @@
 {
     const unsigned size = shorthand.length();
 
     // Begin by collecting the properties into a vector.
     HeapVector<Member<const CSSValue>> values(size);
     // If the below loop succeeds, there should always be at minimum 1 layer.
     size_t numLayers = 1U;
 
     for (size_t i = 0; i < size; i++) {
         values[i] = m_propertySet.getPropertyCSSValue(shorthand.properties()[i]);
+
         if (values[i]->isBaseValueList()) {
             const CSSValueList* valueList = toCSSValueList(values[i]);
             numLayers = std::max(numLayers, valueList->length());
         }
     }
 
     StringBuilder result;
 
     // Now stitch the properties together. Implicit initial values are flagged as such and
     // can safely be omitted.
@@ skipping 193 matching lines @@
             builder.append(", ");
 
         const CSSValue& xValue = repeatXList ? repeatXList->item(i % repeatXList->length()) : repeatX;
         const CSSValue& yValue = repeatYList ? repeatYList->item(i % repeatYList->length()) : repeatY;
         appendBackgroundRepeatValue(builder, xValue, yValue);
     }
     return builder.toString();
 }
 
 } // namespace blink